As shown in FIG. 1, a turbofan engine 10 is typically attached to an aircraft 12 by an engine pylon 50. The engine 10 includes a nacelle 20 which can include an inlet portion 21, a fan cowl portion 23 and a thrust reverser portion 25. As shown in FIG. 1, the pylon 50 can be covered by one or more aerodynamically shaped fairings 18. A forward-most portion of the fairing 19 that is proximate to the fan case portion 23 of the nacelle 20 is sometimes referred to as a “thumbnail” fairing due to its thumbnail-like shape. The thumbnail fairing 19 provides an aerodynamic transition between the nacelle 20 and the pylon fairings 18.
As shown in FIG. 2, the fan cowl portion 23 of the nacelle 20 can include two fan cowl doors 23a, 23b disposed on opposite sides of the engine 10 and the fan case 40. When the fan cowl doors 23a, 23b are in their closed positions, the doors 23a, 23b and fan case 40 define an enclosed annular region 49 around the fan case 40. As also shown in FIG. 2, the fan cowl doors 23a, 23b can be upwardly pivoted to their open positions in order to provide access to the fan case 40 and other engine components (not shown) located within the annular region 49. As shown schematically in FIG. 2, the fan cowl doors 23a, 23b can be pivotally attached to opposite sides of a fan cowl support 30 by one or more hinges 47. As shown in FIGS. 1 and 2, the fan cowl support 30 is typically positioned above the fan case 40 and forward of the pylon 50, and can be substantially coextensive with the width of the fan cowl 23. As also shown in FIGS. 1 and 2, a thumbnail fairing 19 can be assembled over the fan cowl support 30.
As shown in FIG. 3, in one prior art arrangement, the fan cowl support 30 is attached to and fully supported by a forward portion 52 of the engine pylon 50 in a forwardly extending cantilevered arrangement. In such an arrangement, the fan cowl support 30 is not connected to or otherwise supported by any portion of an engine fan case 40. Due to its elongated shape and cantilevered arrangement, such a fan cowl support 30 is sometimes referred to as a “diving board.” As shown in FIG. 4, in another prior art arrangement, the fan cowl support 30 is attached to and fully supported by an underlying fan case 40. In such an arrangement, the fan cowl support 30 is not connected to or otherwise supported by any portion of an engine pylon 50. As shown in FIGS. 3 and 4, the sides of the fan cowl support 30 can include a plurality of spaced hinges 47 for pivotally connecting the fan cowl doors 23a, 23b (shown in FIG. 2) to the fan cowl support.
Because fan cowl supports 30 previously have been attached either only to an engine pylon 50 or only to an engine fan case 40, relative movements between the pylon 50 and fan case 40 which can occur during aircraft operation can cause relative movements between cowls and/or fairings that are attached to the fan cowl support 30, fan case 40 and/or pylon 50. Such relative movements can cause gaps to temporarily form between adjacent cowls and/or fairings. For example, as indicated in FIG. 1, gaps can form between the nacelle inlet 21 and the fan cowl 23 at region “a,” between the nacelle inlet 21 and the thumbnail fairing 19 at region “b,” between the fan cowl 23 and the thrust reverser section 25 of the nacelle 20 at region “c,” and between the thumbnail fairing 19 and the pylon fairing 18 at region “d.” When such gaps are sufficiently large, the gaps may interfere with desired air flow patterns around the nacelle 20 and the pylon 50 if left unsealed. Accordingly, special seals can be required along junctures between adjacent cowl sections and/or fairings that are prone to such gaps in order to ensure that substantial gaps do not form and that desired air flow patterns are maintained. Such sealing solutions can be complex and expensive to implement.
Therefore, there is a need for a fan cowl support system and a method of supporting a fan cowl on a turbofan engine that minimizes relative movements between nacelle cowls and/or pylon fairings, and which reduces or substantially eliminates the need for complex sealing arrangements along joints between adjacent fan cowl sections and/or fairings.